my intake cam snapped?!!?
Mar 10, 2009, 09:12 PM
#16
so today the end of my intake cam snapped off.. this is a 9 btw, it threw off the timing belt obviously and tore the crap out of the timing cover. so i pulled off what was left of it and the cam gear just fell off, i have not done anything else.
what could have caused this?? just camshaft failure? not sure i believe that, they where kelfords. seems like more 9s are doing it rather than 8s. maybe the mivec gear is gay?
what could have caused this?? just camshaft failure? not sure i believe that, they where kelfords. seems like more 9s are doing it rather than 8s. maybe the mivec gear is gay?
Mar 10, 2009, 11:13 PM
#20
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I think the integrity of the cam was compromised during shipment or storage..if a cam doesn't lay on a flat even surface... after about 24 hours the cam's balance can shift and in turn the integrity of the cam may become compromised.
Mar 11, 2009, 08:32 AM
#24
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Can you explain a little further as to what exactly you were doing and what happened when the cam snapped? Were you using stock springs, what RPM and boost, was the tensioner replaced, conditions during the break, etc. ?
There has to be a logical cause to this as cams don’t snap by themselves like that, they need a lot of force to do that. It has happened before with other brands of EVO9 cams, with cores from various sources, but I am not sure what the cause of that was because I was not involved in the discussions.
Kelford has done some testing in their labs, (destructive and non destructive) and found no fault with the castings.
It is near impossible to break these cams with a rotational motion, the only way they could replicate the breakage was by side impact. The only side impact that happens in operation is from belt harmonics which can be caused by various things.
All I know is it took a lot of force for them to break that cam in testing, that amount of force is not normal in the engine.
Some possible causes may stem from;
Spring coil bind
Belt tension
Valve spring harmonics, (trying to run the stock spring at extended rpm and boost)
Not replacing the tensioner with a new unit when installing
Etc.
If you could give us more information on this particular incident we may be able to point you in the right direction.
There has to be a logical cause to this as cams don’t snap by themselves like that, they need a lot of force to do that. It has happened before with other brands of EVO9 cams, with cores from various sources, but I am not sure what the cause of that was because I was not involved in the discussions.
Kelford has done some testing in their labs, (destructive and non destructive) and found no fault with the castings.
It is near impossible to break these cams with a rotational motion, the only way they could replicate the breakage was by side impact. The only side impact that happens in operation is from belt harmonics which can be caused by various things.
All I know is it took a lot of force for them to break that cam in testing, that amount of force is not normal in the engine.
Some possible causes may stem from;
Spring coil bind
Belt tension
Valve spring harmonics, (trying to run the stock spring at extended rpm and boost)
Not replacing the tensioner with a new unit when installing
Etc.
If you could give us more information on this particular incident we may be able to point you in the right direction.
Mar 11, 2009, 09:47 AM
#26
On a customers car, have had two of the Kelford Mivec cams break. One lasted six months, a decent amount of miles of use. Broke at the end of the Mivec journal. Got another set of the same cams. Lasted a couple months. Less than 500 miles. Broke in a different spot.
For reference. First one broke on a stock head and motor. Less than 10,000 mile car. Second one broke on a built motor and head. Using a stock belt, tensioner. I've done hundreds of DSM belts and now a hundred plus EVO cam installs and or belts. Never had any of them break a belt, jump time or break a cam.
Cosworths use the same cores. Same casting marks, grind marks, die marks. Was told last year that some of the Cosworths had broken also.
You never see a stock cam or an HKS cam break.
For reference. First one broke on a stock head and motor. Less than 10,000 mile car. Second one broke on a built motor and head. Using a stock belt, tensioner. I've done hundreds of DSM belts and now a hundred plus EVO cam installs and or belts. Never had any of them break a belt, jump time or break a cam.
Cosworths use the same cores. Same casting marks, grind marks, die marks. Was told last year that some of the Cosworths had broken also.
You never see a stock cam or an HKS cam break.
Last edited by Early EVO; Mar 11, 2009 at 09:51 AM. Reason: added
Mar 11, 2009, 09:54 AM
#27
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Can you explain a little further as to what exactly you were doing and what happened when the cam snapped? Were you using stock springs, what RPM and boost, was the tensioner replaced, conditions during the break, etc. ?
There has to be a logical cause to this as cams don’t snap by themselves like that, they need a lot of force to do that. It has happened before with other brands of EVO9 cams, with cores from various sources, but I am not sure what the cause of that was because I was not involved in the discussions.
Kelford has done some testing in their labs, (destructive and non destructive) and found no fault with the castings.
It is near impossible to break these cams with a rotational motion, the only way they could replicate the breakage was by side impact. The only side impact that happens in operation is from belt harmonics which can be caused by various things.
All I know is it took a lot of force for them to break that cam in testing, that amount of force is not normal in the engine.
Some possible causes may stem from;
Spring coil bind
Belt tension
Valve spring harmonics, (trying to run the stock spring at extended rpm and boost)
Not replacing the tensioner with a new unit when installing
Etc.
If you could give us more information on this particular incident we may be able to point you in the right direction.
There has to be a logical cause to this as cams don’t snap by themselves like that, they need a lot of force to do that. It has happened before with other brands of EVO9 cams, with cores from various sources, but I am not sure what the cause of that was because I was not involved in the discussions.
Kelford has done some testing in their labs, (destructive and non destructive) and found no fault with the castings.
It is near impossible to break these cams with a rotational motion, the only way they could replicate the breakage was by side impact. The only side impact that happens in operation is from belt harmonics which can be caused by various things.
All I know is it took a lot of force for them to break that cam in testing, that amount of force is not normal in the engine.
Some possible causes may stem from;
Spring coil bind
Belt tension
Valve spring harmonics, (trying to run the stock spring at extended rpm and boost)
Not replacing the tensioner with a new unit when installing
Etc.
If you could give us more information on this particular incident we may be able to point you in the right direction.
Mar 11, 2009, 10:06 AM
#30
Ouch man, sorry to see that! 
It looks very similar to what happend to tnt1106 with his GSC S2 MIVEC cams.
I am in the process of fixing up my own car after a cam issue. Luckily not as catastrophic as either of yours, but after seeing these issues I am really questioning both GSC S2's and Kelfords TX272! The two cams that are at the top of my list of replacements!
What gives? Is it the case that these issues are limited to the MIVEC cams? Has anybody seen a case of such catastrophic failure on an Evo 8?
From looking at the breakaway of your cam though, I have to say it looks like a structural fracture. Very likely to be a materials flaw in the core just like tnt's cams. Keep us posted as to how Kelford deals with your situation.
It looks very similar to what happend to tnt1106 with his GSC S2 MIVEC cams.
I am in the process of fixing up my own car after a cam issue. Luckily not as catastrophic as either of yours, but after seeing these issues I am really questioning both GSC S2's and Kelfords TX272! The two cams that are at the top of my list of replacements!
What gives? Is it the case that these issues are limited to the MIVEC cams? Has anybody seen a case of such catastrophic failure on an Evo 8?
From looking at the breakaway of your cam though, I have to say it looks like a structural fracture. Very likely to be a materials flaw in the core just like tnt's cams. Keep us posted as to how Kelford deals with your situation.